Inverted perovskite/silicon V-shaped tandem solar cells with 27.6% efficiency via self-assembled monolayer-modified nickel oxide layer

A novel inverted perovskite/silicon V-shaped tandem solar cell is proposed based on an elaborate design of photon matching and management, in which the underutilized above-bandgap photons and unutilized below-bandgap photons are reflected from two inverted perovskite solar cells (PSCs) to both sides of a bifacial silicon solar cell (SSC) and allows half-usage of silicon for competitive power output. Here we conduct the interface engineering and the photon management through an IWO (tungsten doped indium oxide)-based inverted PSC with a self-assembled monolayer (SAM)-modified NiO_x hole-transport layer (HTL) and a solution-processed PCBM ([6,6]-phenyl-C₆₁-butyric acid methyl ester) electron transport layer (ETL) to simultaneously improve the performance of the inverted PSC and optimize the energy allocation for the bifacial SSC. The NiO_x/SAM HTL improved the power-conversion efficiency (PCE) of the PSC by enhancing charge extraction, while the PCBM ETL dramatically suppressed the diffuse reflection as well as parasitic absorption of the PSC by smoothing the reflective silver back electrode. These enabled a 19% PCE for a perovskite sub-cell with average near-infrared reflectance of over 85% and an 8.8% PCE for a bifacial heterojunction silicon sub-cell, yielding a power-conversion efficiency of 27.6% for a V-shaped tandem cell. This work proposes a promising V-shaped tandem cell with inverted PSCs and half-usage of SSCs, which is beneficial for reducing carbon emissions in the silicon cell industrial chain.